I read the book. It felt a little like creeping behind the bike sheds at school to have a cigarette, as if an ID cancer might seize control of my synapses. The temptation was irresistible. What I discovered was an arresting book about science, which is what drew Nagel. But it is close to vacuous when it comes to the theology. That, it seems to me, is the problem with ID.

To a non-specialist like myself, Meyer seemed to capture very well the depth of the mystery that the origin of life is to modern science – essentially how DNA, as an astonishingly precise and complex information processing system, could possibly have come about. It's analogous to the monkey-bashing-at-a-typewriter-and-producing-Shakespeare problem, except that with DNA it's even more intractable: you've also got to account for how typewriters and language arose too, they being the prerequisites for the possibility of the prose, let alone the prose of the Bard.

That said, it's because of the inscrutable nature of life's origins that I found the book theologically unsatisfying. It proposes, in essence, an argument from ignorance.

The ID hypothesis Meyer conveys is, roughly, that life is, at base, an information processing system, information that is put to a highly specific purpose, and that the best explanation for the source of such a system is one that is intelligent. Only an intelligence could get the system going, as it were. It can't be put down to chance, since by massive margins there hasn't been nearly enough time since the Big Bang for the random encounters of organic compounds to form such highly specified self-replicating systems. Neither can it be put down to self-organisation, since what DNA requires to work is not general patterns, but the fantastically fine-grained and specific activity of proteins and amino acids. Intelligent design is, then, the best hypothesis to date. But that qualification, "to date", is the problem.

For in truth, no one really knows what life is, let alone how it arose. The work in the last half century or so on DNA has only deepened the problem – vastly deepened it. "The more we know, the more we don't know," to quote Omar from The Wire. It may well be the case that the theoretical underpinning of Meyer's argument, information theory, is an inadequate way of understanding how DNA works, for all that bioinformatics is big right now. The assumptions of classical mechanics provided the theoretical underpinning for Newton's view of the universe, and were integral to his version of ID: a deistic belief in a divine architect. But then came quantum mechanics and relativity. God the divine geometer was history. God the IDer will surely go the same way too.

To appeal to an immaterial intelligence as the source of life's informational specificity is as premature as assuming that Darwinian processes can account for life's origin – not a mistake Darwin himself made, of course. A theist might suggest that the evidence to date points to God, as a neo-Darwinian might suggest it points to natural selection. But in so doing, both rely on prior metaphysical commitments – that divine agency or natural selection, respectively, can be made into "theories of everything".

So much for the argument from ignorance. And from it follows the major theological objection to ID: assuming that God could be a scientific explanation at all. To do so has long been observed to be ridiculous.

Socrates knew as much. On the day of his execution, Plato portrays him asking his followers why he is sitting in the prison cell awaiting the hemlock. Is it because his kneebone is connected to his thighbone and they have, in conjunction with all the other parts of his body, propelled him to this juncture? No. He is facing his death because he believes in the moral imperative of facing the judgment of the Athenian jury. Belief and science are two different kinds of explanation, one moral, the other material. To opt for one, when the other is required, is as laughable as thinking that the theory of optics explains the art of Van Gogh.

God is something else again, which Thomas Aquinas, the medieval theologian, explored in the notion that creation is "out of nothing". The "ex nihilo" is not supposed to be a demonstration of God as a scientific whizz-kid, so amazing that he doesn't even need matter to make the cosmos. Rather, it's to say that the universe was created with no instrumental cause. It is the original free lunch, offered purely out of God's love. You can argue about whether you'd have picked what's on the menu. But to insert God into the causal chain is a category mistake and, in fact, technically a blasphemy. It implies that God is one more thing along with all the other things in the universe. You're not dealing with divinity there, but an idol.

If all that seems too philosophical, then you can turn to William Blake. He mocked Newton's God in the famous image portraying Newton, sitting on some slimy rocks, bending over rolls of diagrams and wielding a compass. The God of ID might be mocked similarly, by portraying The Ancient of Days sniffing and seasoning the prebiotic soup.